mjm yachts 50z Downeast, Owner'S Manual

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8.1
8.2
GENERAL
This is a very important section. Raw water
(seawater) is used to cool the engines and
generator. It is also used for Seakeeper Gyro
bearings and for the air-conditioning system..
Wherever raw water enters the boat, it does so through
a seacock, which is a thru-hull valve with double-
clamped hoses..
There are 5-6 Raw Water intake
thru hulls and Groco Raw Water Strainers that
should be checked with frequency
… particularly in weedy areas daily. These strainers
keep seaweed and other particles from plugging up engine cooling systems and causing
overheating and potentially severe damage.
RAW WATER STRAINERS These raw water strainers are:
1 for each engine on top of the engines
1 for the Seakeeper Cooling System (shown as the left of two) in the Utility Room
1 for the Air Conditioning System (shown as the right of two) in Utility Room under the
ladder
1 for the Generator located next to the generator.
These are designed for easy maintenance as long as you pay attention to the instruction
to “HAND TIGHTEN ONLY”. You don’t want to be looking for wrenches in the middle of a
harbor with your generator overheating because someone put their arms, shoulder and
back into tightening the lids down. BE SURE TO CLOSE THE SEACOCK BEFORE
OPENING THE STRAINER THEN REMEMBER TO OPEN THE SEACOCK
AFTERWARDS.
NO WATER FLOW?
If you don’t see water flow in the clear tops of the Groco Raw Water Strainers and you know the
striainers are clean and the seacock thru-hull valves are open then there is an obstruction blocking
the intake opening of the thru-hull
… most likely a plastic bag. It will have to be removed either by
going over the side to remove it or using the fresh water washdown hose and trying to blow it back
out thru the intake line to the strainer with the valve open.
CHAPTER 8 RAW WATER SYSTEM